Field of the Invention
The present invention relates to physical uplink control channel (PUCCH) cells in a communication network using carrier aggregation.
Related Background Art
In E-UTRA, carrier aggregation (CA) has been introduced, where two or more component carriers (CCs) are aggregated in order to support wider transmission bandwidths up to 100 MHz. In CA it is possible to configure a UE to aggregate a different number of CCs originating from the same eNodeB (eNB) of the communication network and of possibly different bandwidths in the uplink (UL) and downlink (DL). When in CA, a UE is always configured with a primary cell (PCell). The PCell is used for security, NAS mobility, and transmission of a PUCCH (including scheduling requests). All other configured CCs are called secondary cells (SCells) and do not have the PUCCH configured. Furthermore, in CA, the possibility to de-activate CCs/SCells in order to reduce the UE power consumption is supported. The UE monitoring activity of a de-activated SCell is reduced (e.g. neither PDCCH monitoring nor CQI measurements are performed) and the UL activity in a de-activated carrier is also stopped (e.g. no SRS is transmitted). Note that the PCell which carries the PUCCH cannot be deactivated.
When there is a problem on the PCell, for example an RLF, all the communication is stopped and the UE tries to re-connect with the communication network through re-establishment. This interrupts the communication and causes delay.
The following meanings for the abbreviations used in this specification apply:
CA Carrier Aggregation
CC Component Carrier
CQI Channel Quality Indication
DL Downlink
eNB evolved NodeB
E-UTRA Evolved UMTS Terrestrial Radio Access
SCell Secondary Cell
PCell Primary Cell
PDCCH Physical Downlink Control Channel
pTAG PCell Timing Advance Group
PUCCH Physical Uplink Control Channel
PUG PUCCH Group
RLF Radio Link Failure
SRS Sounding Reference Signal
TAT Timing Advance Timer
UE User Equipment
UL Uplink
UMTS Universal Mobile Communications System